Cab company thugs frame an immigrant woman for a bombing, but her husband, friends, and the mayor help save her from deportation.
Taxi-driver Joe Benton (Spencer Tracy) picks up his wife Anna Benton (Luise Rainer), and they kid each other. Her brother Paul Roya (Victor Varconi) is hit by a Comet Cab, and others join the fight. John C. Andrews (Oscar O'Shea) tells Beecher (William Demarest) to stop strong-arming the independents. Paul gets a job with Comet Cab. At Anna's birthday party Joe and Paul give her a radio. Anna is going to have a baby. Anna puts a sweater and a rain-coat into a box for Buddy (John Arledge) to take to Paul at Comet Cab. A bomb goes off, and a guard shoots Paul. Beecher says that they will be working for Comet Cab for a long time. Buddy and Anna are questioned. Beecher demands all the independent drivers be arrested; but District Attorney Gilbert (Paul Harvey) plans to deport Anna instead.
After a church service Anna is arrested; but she runs off and is hidden by friends. Detectives look for her without success. Joe visits Anna by the window with an ice cream cone. Danny Devlin (Guinn Williams) drinks a quart of milk for the detectives. Joe tells Anna how the detectives told him they caught her. The District Attorney tells the drivers that Comet Cab only wants the girl. Joe is followed on a roof, but they find only an old man. Joe and the others are arrested. Wives meet to count their money. Anna goes out and calls the Mayor (Charley Grapewin) to offer herself for the men.
Joe goes on the ship to say good-bye and promises Anna he will follow her; but she tells him to stay. Joe raises money to get her a better room. Buddy complains to Beecher for giving him only $200 and says he wrote a letter. Joe and Mike Edwards (Eddie Quillan) find the letter to the D. A. When Buddy comes home, Joe grabs him. They track down the Mayor at a boxing banquet. Buddy tells him that Beecher did the bombing and had the guard shoot Paul. Joe pleads for Anna. Mike drives them to the pier fast with a siren. The Mayor and D. A. demand to see the captain. The Comet Cab drivers go to the pier. Joe tells Anna that she doesn't have to go. Anna is taken to an ambulance. The Comet Cab drivers arrive and start a fight. The Mayor allows the boxers (including Jack Dempsey) to join in. In the final scene Anna's baby boy is Christened after all the men.
This story illustrates how immigrants have less rights than citizens and how some hoodlums try to use violence to give themselves a job; but the friendship of the independent cab drivers enables them to overcome their opponents.